Micro/nanobubble aeration promotes rapid and stable partial nitrification by strengthening the synergistic activity of functional microbial communities in the treatment of low-strength rural wastewater

Résumé fourni par la source

Partial nitrification (PN) offers significant economic and environmental advantages; however, achieving a rapid start-up and stable long-term performance remains a major technical challenge globally. In this study, we demonstrate for the first time that micro- and nano-bubble (M/NB) technology can serve as a simple yet effective strategy for the rapid startup and sustained stability of PN in real rural sewage, while simultaneously achieving >70% energy saving via the application of M/NB aeration in sequencing batch reactors (SBRs). The oxygen transfer coefficient (K La ) of M/NB aeration was circa 8.4 times higher than that of conventional bubble (CB) aeration. Unlike conventional macrobubble systems, the M/NB-aerated reactor achieved a nitrite accumulation ratio (NAR) of 90.3% within just two days. Once established, the M/NB-PN reactor maintained a high NAR (90–97%) despite substantial seasonal fluctuations in ammonia loading and temperature, demonstrating excellent operational robustness. The enhanced performance was attributed to the preferential stimulation of ammonia-oxidizing bacteria (AOB) over nitrite-oxidizing bacteria (NOB) under M/NB aeration. This shift promoted the enrichment of Nitrosomonas (AOB) while effectively suppressing Nitrospira (NOB). Furthermore, the relative abundances of the functional genes amoA and hao in the M/NB-aerated reactor were more than eightfold and fourfold higher, respectively, compared to those observed under conventional aeration conditions. Batch experiments confirmed the reproducibility of this strategy, successfully achieving PN using non-PN-acclimated seed sludge. Overall, this study introduces a practical and energy-efficient method for the rapid start-up and stable maintenance of PN, providing a promising foundation for the implementation of partial nitrification/anammox (PN/A) and advanced nitrogen removal technologies.

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